Performance comparison of 1 watt Ka-band MMIC amplifiers using pseudomorphic HEMTs and ion-implanted MESFETs

We have demonstrated a high-gain, high-efficiency Ka band three-stage MMIC power amplifier providing >1 watt CW output power, >20 dB power gain, with an average 35% power-added efficiency (378 peak) over a 26.5 to 28 GHz band using 0.25 /spl mu/m AlGaAs/InGaAs pseudomorphic HEMT (HEMT) process technology. The pHEMT amplifiers exhibit third-order intermodulation products >29 dBc with the output power backed off by 5 dB. As an alternate low-cost solution, we processed three wafers of the Ka-band monolithic amplifier designed with pHEMT technology using direct ion-implanted 0.2 /spl mu/m GaAs MESFETs achieving >1 watt CW output power, >18 dB power gain, with an average 24% power-added efficiency (27% peak) over the band. The MESFET amplifiers demonstrate third-order intermodulation products >21 dBc with the output power backed off by 5 dB. All amplifier results reported here contain no de-embedding of fixture and connector losses. This paper presents 0.25 /spl mu/m pHEMT and 0.2 pm MESFET device results, as well as amplifier design and performance over a 26.5 to 28 GHz band.